1. Field of the Invention
The present invention relates to a paper feeding apparatus of a printing device, and more particularly, to a paper feeding apparatus having an improved structure for supplying paper from a cassette to the inside of the printing device.
2. Description of the Related Art
In a typical printing device such as a printer or a copying machine, a paper feeding apparatus receives a multitude of paper sheets and supplies that paper into the body of the printing device in sequence.
As shown in FIG. 1, a conventional paper feeding apparatus includes a cassette 20 capable of moving along guide rails 11 and 12 provided in the body 10 of the printing device and for receiving papers therein. The feeding apparatus also includes a pickup roller 13, rotatably installed in the body 10, for drawing out the paper received in the cassette 20.
The cassette 20 includes side guide members 21 and 22 and a rear guide member 23 slidably installed, for supporting both sides and the rear end portion of the received paper, respectively. The cassette also includes finger members 25 and 26 for pressing and supporting corner portions of a fore end of the received paper, extended from the side guide members 21 and 22, and a receiving plate 24 for receiving paper and lifting the fore end portion of the received paper toward the finger members 25 and 26.
Reference numeral 13a denotes a rotation shaft of the pick-up roller 13, whereas arrow `A` indicates the direction in which the cassette 20 is connected to the body 10 of the printing device, and arrow `B` indicates the supply direction of the paper.
As shown in FIG. 2, the paper received in the cassette 20 is supplied by rotating the shaft 13a. The pick-up roller 13 rotates, and thus an uppermost paper 100 tightly contacting the pick-up roller 13 is fed in the direction indicated by arrow `B`. At this time, the fore end corner portion of the paper 100 is caught by the finger members 25 and 26, so that the fore end portion of the paper is partially folded, which causes a curled portion `C` indicated by dotted lines. When the pick-up roller 13 continues to rotate, the paper 100 is transferred in the direction indicated by arrow `B`, the fore end corner portion of the paper 100 slips out from the finger members 25 and 26 and is supplied to the inside of the body 10.
The curled portion `C` facilitates drawing and supplying only the uppermost paper sheet from the cassette 20 to the inside of the body 10. That is, the curled portion suppresses the multitude of remaining supply sheets of paper at once. Thus, the curled portion must be appropriately formed in order to smoothly and repeatedly supply individual sheets of paper. A distance `D` between the pick-up roller 13 and the finger members 25 and 26 is set considering the appropriate forming of the curled portion. That is, when the distance `D` is too long or short, the curled portion is inappropriately formed, thus crumpling or tearing the paper.
However, by the above-described paper feeding apparatus, when the size of the received paper is changed, for example A4 to A3, the finger members 25 and 26 together with the side guide members 22 and 21 move to correspond to the size of the changed paper. However, the pick-up roller 13 is fixed in a predetermined position. Thus, the distance `D` is changed, so that the curled portion may not be appropriately formed according to the change in the paper size.